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  1. #1
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    balanced and differential input signal

    Hi could anyone please tell me the difference between balanced and differential input. Or are they both the same??? I cam across

    "DIFFERENTIAL INPUTS - A signal input circuit where SIGNAL LO and SIGNAL HI are electrically floating with respect to ANALOG GROUND"

    Balanced signaling is two conductors (with an optional shield) that have equal impedance to ground.

    Differential signaling is two conductors (with an optional shield) transmitting the same signal at opposite polarity"

    In one site it was put diff input is with respect to analog ground and in another just mentioned that they are opposite in polarity and balanced input have equal impedance to ground. Also can anyone please explain what "equal impedance to ground means"

    Does it mean that the input potential to both inputs (+ and -) are the same? I am not familiar with concept of impedance. Its something that i am little not clear. I thought impedance is something that just is used to allow or block the signal at the input (if high or low impedance). But what does equal impedance to ground mean??? Thank you!!!

    •   Alt30th October 2015, 19:46

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  2. #2
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    Re: balanced and differential input signal

    First take a look at this explanation of balanced signals (cables).

    Now realize a balanced signal is a differential signal.

    The primary difference is the balance signal is referenced to ground for both signals. A differential signal (e.g. LVDS) for digital logic is both differential and contains a DC bias. Therefore the signals are not referenced to ground but to some intermediate voltage value above ground.



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